Human dendritic cell 1 and dendritic cell 2 subsets express FcεF-RI:: Correlation with serum IgE and allergic asthma

Background: Type 1 dendritic cells (DC1) express the high-affinity IgE receptor (FcepsilonFRI); however, the regulation of FcepsilonRI expression by DCs is not well understood. Type 2 DC (DC2) expression of FcepsilonRI has not been demonstrated. Objective: We hypothesized that DC2 cells also express FcepsilonRI and that expression of FcepsilonRI by the DC1 and DC2 subsets correlates with serum IgE and allergic asthma disease status. Methods: To test these hypotheses, we quantitated FcepsilonRI a chain expression by the peripheral blood precursor DC1 (pDC1) and pDC2 subsets by using flow cytometry. Results: FcepsilonRI was expressed by the pDC1 and pDC2 subsets, as well as tissue DCs from tonsils. Relative FcepsilonRI expression by basophil, pDC1, and pDC2 subsets was 12:6.5:1, respectively. In both pDC subsets, FcepsilonRI expression was significantly greater in allergic asthmatic subjects than in nonatopic control subjects. pDC1 and pDC2 expression of FcepsilonRI was highly correlated to serum IgE concentration. The pDC1, pDC2, and basophil subsets demonstrated a similar magnitude of increase in FcepsilonRI expression relative to changes in serum IgE. Conclusions: FcepsilonRI expression is characteristic of both the DC1 and DC2 subsets. Furthermore, FcepsilonRI expression by these cells is highly correlated to serum IgE and to basophil FcepsilonRI expression and is greater in subjects with allergic asthma. These data support the concept that novel therapeutic approaches directly targeted at FcepsilonRI expression would affect both the sensitization and the effector phases of the allergen-specific immune response.